Whitney Houston was a victim of sexual abuse as a child and she took that secret with her to her grave at age 48, family members reveal in a documentary that premiered at the Cannes festival Wednesday.

In Whitney, half-brother Gary Garland says he was abused when he was young by cousin Dee Dee Warwick, sister of Dionne Warwick, and he believes Whitney was as well, reports Vanity Fair, which describes Kevin Macdonald's film as "heart-wrenching." Mary Jones—Houston's aunt, and the person who found her body after her death in 2012—confirmed to Macdonald that the singer told her she had been abused by Warwick, who died in 2008, the Telegraph reports.

Jones said she thought Whitney never told mother Cissy Houston because she was "ashamed" and afraid of the repercussions.

Macdonald tells Deadline that after watching footage of Houston, he began to suspect she had been abused.

"There was something preventing her, in some way, from expressing her real self. She felt uncomfortable in her own skin in almost every interview there was with her," he says.

"And I thought that was a very strange thing, and it kind of reminded me of people I’d seen who had suffered from abuse, just in their body language and their sense of holding something back." He says he believes Houston's self-destructive behavior, including drug use, was linked to the abuse.

The person you see in the film, he says, is somebody "who doesn't know who they are and who is in pain because they can’t talk about the central problem in their life, which I think came from the abuse."